The most likely explanation is that it hurts because his brain is processing it incorrectly.
If the announcements happen without warning, they could also be startling him badly. Being startled is hugely unpleasant for me- it makes me feel disoriented and detached from my body, and it gives feelings like lightning bolts through my head- it's possible that your son experiences something similar.
Quote:
In autism the sensory memory is longer and we cannot filter out anything.
Yep.
Go into an even moderately noisy room sometime and pay attention to
everything.
It's unpleasant, isn't it?
This is what people with autism deal with all the time.
Now add unexpected new noises to that. Can you understand why it would be upsetting?
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Music Theory 101: Cadences.
Authentic cadence: V-I
Plagal cadence: IV-I
Deceptive cadence: V- ANYTHING BUT I ! !! !
Beethoven cadence: V-I-V-I-V-V-V-I-I-I-I-I-I-I-I-I-I-I
-I-I-I-I-I-I-I-I! I! I! I I I